Clean Tech

Wave Power: Let The Oceans Rise

A few decades ago, we lived in an era when oil was gold. The advent of the information age has made data the new gold. But honestly, energy (any form of energy) will always remain a goldmine.

Traditional energy sources might be passé, and renewable energy sources might be in vogue, but the new frontiers of energy sources hold promise for the future.

Coal and natural gas have a limited supply, and solar or wind energies are not constant throughout the year, but some avenues can provide energy around the clock.

Wave energy–the power of waves–is a promising new energy source that can alter the power dynamics in the world.

Two-thirds of all countries on the planet have an ocean shoreline. Waves never (technically) die. Violent waves–in case of a storm–or flat waves–in case of calm–are the necessary flavors of waves. These extreme conditions are not ideal but can be leveraged, nonetheless.


The basics of wave energy

Waves form when the wind blows over the surface of the water. Wave energy is electrical energy generated by harnessing the up-and-down motion of ocean waves. Unlike tidal energy, which uses the ebb and flow of the tides, wave energy uses the vertical movement of the surface water that produces tidal waves.

Wave energy is a concentrated form of solar power generated by the action of the wind blowing across the surface of the ocean. When the sun’s rays strike the Earth’s atmosphere, they warm it up. The differences in the temperature of the air around the globe cause it to move from hotter to cooler regions, resulting in winds.

As the wind passes over the surface of the oceans, a portion of its kinetic energy is transferred to the water below, generating waves.

(Gravity also plays a role, but that topic is for another discussion)

The ocean is a vast storage collector of energy transferred by the sun to the oceans, with the waves carrying the transferred kinetic energy across the surface of the oceans. 

The waves can travel (or propagate) long distances across the open oceans with very little loss in energy. As they approach the shoreline and the depth of the water becomes shallower, their speed slows down, but their size increases. When the wave crashes onto the shoreline, it releases an enormous amount of kinetic energy that can be used to produce electricity.

The potential areas for wave energy production are in the latitudes with the highest winds (latitudes 40°–60° N and S) on the eastern shores of the oceans.


Diving deeper

In its simplest terms, an ocean wave is the up-and-down vertical movement of the seawater that varies sinusoidally with time. This sinusoidal wave has high points called crests and low points called troughs.

The difference in the height of a wave between the crest and the trough is called the peak-to-peak amplitude.

The amplitude of an ocean wave depends on the weather conditions at that time, as the amplitude of a smooth wave, or swell, will be small in calm weather but larger in stormy weather with stronger gales as the sea water moves up and down.

The distance between each successive crest or trough is known as the wave period (T). It is the time (in seconds) between each crest of the wave. For a gentle swell, this period may be very long, but for a stormy sea, this period may be very short as each wave crashes onto the one in front.

The reciprocal of this time ( 1/T ) gives us the fundamental frequency of the ocean wave relative to some static point. Smaller periodic waves generated or superimposed onto this primary wave, such as reflected waves, are called harmonic waves.  

The frequency and amplitude characteristics of a wind-generated wave depend on the distance the wind blows over the open water (called the fetch), the length of time the wind blows, the speed of the wind, and the water depth.

Waves transport energy from where they were created by storms far out in the ocean to a shoreline. However, a typical ocean wave does not resemble a perfect sinusoid. They are irregular and more complex than a simple sinusoidal wave. Only the steady up-and-down movement of a heavy swell resembles a sinusoidal wave. Rest are chaotic–actual sea waves are a blend of different frequencies, wave heights, and directions.


Devising the devices

Wave power is typically produced by floating turbine platforms or buoys that rise and fall with the swells. However, it can be generated by exploiting the changes in air pressure occurring in wave capture chambers that face the sea or changes in wave pressure on the ocean floor.

Based on the distance between the energy conversion device and the shoreline, wave energy devices can be classified as shoreline devices, nearshore devices, and offshore devices. 

Shoreline devices are fixed to or embedded in the shoreline; they are both in and out of the water.

Nearshore devices extract the wave power directly from the breaker zone and the waters immediately beyond the breaker zone (at 20m water depth).

Offshore devices or deep water devices are the farthest out to sea and extend beyond the breaker lines utilizing the high-energy densities and higher power wave profiles available in the deep water waves and surges.


A roadblock to glory

Despite the enormous energy potential of wave power, technical challenges remain. Building and operating wave energy plants are generally expensive. Cables, turbines, and other infrastructure could potentially harm marine life. Since the plants rely on coastal locations, they may not be able to support whole populations.

Research funding is low compared with that supporting solar, wind, and other renewable forms of energy. Therefore, the process of experimentation and refinements with different wave energy collector designs is not as well developed.

Marine technologies hold great potential, but additional policy support for energy research, development, and demonstration is needed.

Here’s a little video takeaway:

How Waves Could Power A Clean Energy Future



Wave Energy and How Wave Energy Creates Electricity

Wave energy: can ocean power solve the global energy crisis? | World Economic Forum

Wave power | Process & Facts | Britannica